羊咩咩 發問於 科學及數學化學 · 1 十年前

Chemistry daily facts

Chemistry Question Urgent. Please really do help if you know the answer.

Explain

a) Lemon juice can be used to remove the brown stains on Chinese wok.

b) Fizzy drink tablets are usually kept in cool dry place.

Thanks

2 個解答

評分
  • YY
    Lv 6
    1 十年前
    最愛解答

    a)brown stains on Chinese wok = rust = Metal Oxide

    Lemon juice contain citric acid

    Acid + Metal Oxide = salt + water

    Hence, Metal Oxide has removed from Chinese wok.

    b)Fizzy drink tablets contain hydrogencarbonate

    Heat and water cause decomposition of hydrogencarbonate to produce carbon dioxide

    To prevent fizzy drink tablets become useless, it should be kept in cool dry place

  • Wilson
    Lv 7
    1 十年前

    a) brown stains on wok = rust = Fe2O3

    lemon contain citric acid

    acid dissolve the oxide.

    b) contain hydrogencarbonate, wet heat and water cause decomposition.

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